1. Field of the Invention
This invention relates to a method of treating fresh shrimp or the like for reducing moisture loss during storage and processing, to in that manner increase yield and at the same time improve the nutritional value and palatability of the final shrimp meat product.
2. Problem Addressed
As explained in a Dec. 14, 1978 report published by David L. Crawford, Program Director, Oregon State University Seafoods Laboratory, Department of Food Science and in Technology, shrimp begin to undergo to a time and temperature dependant degradative change in their muscle proteins immediately after they are harvested. This degradative process results in a decrease in the cooked meat yield. The degradative process involves a loss of moisture from the shrimp both during both storage and processing. Studies by George Garnatz, Norbert H. Volle and Fred E. Deatherage indicate the moisture loss during cooking alone can result in losses from 33% to 50%, based on the weight of the green peeled shrimp meat. Liquids that are lost contain significant amounts of soluble protein minerals and other nutrients. This loss results in reduced nutritional value and palatability losses in addition to a reduced yield.
3. Description of the Prior Art
The aforementioned report by David L. Crawford indicates that moisture losses caused by cooking can be decreased by treating the round shrimp with condensed phosphates prior to processing. The report discusses experimental phosphate pretreatment involving the use of a commercially available mixture of sodium tripolyphosphate and sodium hexametaphosphate. In these experiments the water in a precooker feed hopper was treated with the phosphate solution.
U.S. Pat. No. 3,620,767, granted Nov. 16, 1971, to William E. Swartz, relates to the use of a molecularly dehydrated phosphate such as either sodium tripolyphosphate or an orthophosphate for increasing the yield of cooked bonito meat. Bonito is a fish similar to tuna. The process involves injecting the phosphate solution into the meat shortly before cooking the meat.
U.S. Pat. No. 3,036,923, granted May 29, 1962, discloses the uses of sodium and potassium molecularly dehydrated phosphates for inhibiting the loss of moisture, soluble protein, minerals, and vitamins from frozen fish on thawing and cooking. The method employed involves dipping the fish fillets into the phosphate solution for two minutes and then draining them for thirty seconds, prior to freezing.
U.S. Pat. No. 2,488,184, granted Nov. 15, 1949, to George Garnatz, Norbert H. Volle' and Fred E. Deatherage discloses the use of several alkaline salts for treating shrimp, both for increasing the yield and improving the quality of the meat. The method involves soaking raw green peeled shrimp (which may or may not have been frozen and subsequently defrosted) in the alkaline salt solution for about two hours. The shrimp is then removed from the solution and cooked in another solution and while hot is placed into ice water and agistated. Thereafter, the shrimp meat is drained and prepared for commercial retail sale or immediate table use.
In order for any method of increasing yield and/or quality to be of commercial importance, it must fit in well with established harvesting and processing practices.
The usual commercial practice for storing fresh shrimp aboard the fishing vessel is to place the shrimp in a hold mixed with crushed or flake ice. A typical known machine for manufacturing flake ice aboard fishing vessels is disclosed by U.S. Pat. No. 3,735,275, granted Feb. 21, 1956 to Lyle E. Branchflower.
Experiments have been conducted with respect to adding chemical compounds to water which is frozen into ice for icing a catch aboard a fishing vessel. Progress Report No. 67, published by the Fisheries Research Board of Canada, discusses experiments with germicidal ices aboard fishing vessels. The chemicals employed were dissolved in tap water immediately prior to freezing, either in 300 lb. blocks in commercial ice plants or in 30 lb. blocks under laboratory conditions. The block was crushed finely before being used to ice the fish. The experiments were conducted on lingcod and lemon sole. It was learned that fish iced with such ices kept longer than fish iced with ordinary ice because the flesh was maintained at a lower temperature, i.e. the ice formed at a lower temperature than plain water ice. The treated fish were studied to determine whether the chemical ice acted to retard bacterial spoilage of the fish.
An article by E. A. Fieger, M. E. Bailey and A. F. Novak, entitled "Chemical Ices For Shrimp Preservation, " appearing in the December 1956 issue of Food Technology, discusses the effect of certain chemical ices on the ice storage life of fresh shrimp, and the relative quality of the treated shrimp. The chemicals investigated were bacteriostatic agents. It was concluded that in general, the quality of the shrimp packed in the chemical ices used in the experiment were slightly superior to that of shrimp packed in commercial plain water ice, but in no instance was the total storage time increased.
The above discussed articles and patents are to be considered a part of my disclosure; it is my desire that they be incorporated by reference into my disclosure.
Additional technology in the patent literature, which together with the above discussed articles and patents should be carefully studied for the purpose of putting the present invention into proper perspective relative to the prior art, is contained within U.S. Pat. No. 1,046,991, granted Dec. 10, 1912, to Alexander Danilevisky; U.S. Pat. No. 2,555,236, granted May 29, 1951, to Ekkehard L. Kreidl and Earl P. McFee; U.S. Pat. No. 2,735,777, granted Feb. 21, 1956, to Albert Meyer and U.S. Pat. No. 2,892,865, granted July 1, 1975, to Alberto Sfeir.